Filming apparatuses such as video cameras and movie cameras are mounted on a tripod via a tripod head. Since the filming apparatuses are required to move within a horizontal plane and a vertical plane so as to follow the movements of an object, the tripod head is integrated with a mechanism to achieve such movements. The tripod head is provided with a drag mechanism for a rotation within a horizontal plane and the drag mechanism and a counterbalancing mechanism for tilting motion in the vertical plane in order to smoothen the moving operation of the filming apparatus. Both of the drag mechanism and the counterbalancing mechanism are configured to achieve the movements of the filming apparatus with a substantially constant operating force.
The counterbalancing mechanism is configured to generate a drag so as to be capable of counterbalancing with a rotation moment generated when the filming apparatus mounted on the tripod head tilts within the vertical plane. A method of generation of the drag is generally on the basis of a spring.
Incidentally, the weights of the filming apparatus are different from one apparatus to another, and hence the counterbalancing mechanism is required to adjust a resilient force that the spring generates to a suitable magnitude corresponding to the weight of the filming apparatus.
In order to cope with such a requirement, a tripod head described in US 2010/0243851 A1is configured with a parent screw which is rotated by an internal gear to adjust the position of a sliding member with respect to the seat and adjust an initial compression state of the spring so as to accommodate cameras having different weights. The tripod head described in US 2010/0243851 A1 is configured in such a manner that the internal gear rotates via a pinion by a rotating operation of a wheel provided so as to project from a side wall of a lower housing.